http://acr.victorz.ca/ or http://assaultcuber.codeplex.com/ - this is an improved version of assaultcube with lots of features added to make online play a bit more fun (things like blood, headshots, etc) ... I tested on windows a couple of days ago, online play works very well, and was good fun.. I ended up playing two or three full rounds, I only meant to test it quickly..

I also made a pet package of AssaultCube Reloaded (it's on the forum and in the akita repo), but I think that one doesn't work with online play anymore.._________________Akita Linux, VLC-GTK, Pup Search, Pup File Search